In conjunction with the Center for Science in the Public Interest (CSPI), Monet Parham, a 41-year-old mother of two, filed a class action against McDonald’s on Wednesday in San Francisco Superior Court, claiming that the fast food chain’s practice of giving away toys with Happy Meals is a form of deceptive advertising to children.

The CSPI also claims that McDonald’s uses Happy Meals toys to circumvent parental control, and to teach children to want unhealthy, calorie-packed foods that are high in salt, sugar and fat. “Marketing to kids is an end-run around parental control,” Stephen Gardner, CSPI’s director of litigation, told NPR. (More on Time.com: Study: Fast-Food Ads Target Kids with Unhealthy Food, and It Works)

CSPI explained its position in a statement it released about the lawsuit:

According to the Institute of Medicine and the American Psychological Association, kids as young as Maya do not have the cognitive maturity to understand the persuasive intent of advertising. Advertising that is not understood to be advertising is inherently deceptive — an idea that CSPI’s lawsuit points out is well established in law. “Every time McDonald’s markets a Happy Meal directly to a young child, it exploits a child’s developmental vulnerability and violates several states’ consumer protection laws, including the California Unfair Competition Law,” said CSPI litigation director Steve Gardner.

Even though Happy Meals television advertising shows brief glimpses of healthier products, such as Apple Dippers and low-fat milk, the default options put into Happy Meals by McDonald’s employees are usually French fries and sugary sodas. In a CSPI study of 44 McDonald’s outlets, French fries were automatically included in Happy Meals 93 percent of the time. Soft drinks were the first choice offered to customers 78 percent of the time.

“I don’t think it’s O.K. to entice children [to get] Happy Meals with the promise of a toy,” Parham said in a press statement, complaining that she was tired of her daughters, ages 6 and 2, coveting the entire set of collectible toys from a “Shrek Forever After” promotion at the restaurant, which would have required weekly Happy Meal purchases to obtain. She added that for her children the McDonald’s visits were about the toys, not the food, and that they were too young to understand the nuance of advertising. (More on Time.com: No Vegetable, No Toy: San Francisco Mimics Parents Everywhere)

As we wrote earlier on Healthland, a recent study by Yale University’s Rudd Center for Food Policy & Obesity found that child-targeted marketing at fast-food restaurants works:

[A] whopping 40% of parents reported that their child asked to go to McDonald’s at least once a week, and 15% of preschoolers’ parents said they fielded such a request every day. Most of the parents gave in: 84% reported bringing their 2-to-11-year-olds to a fast food restaurant within the previous week.

Parham and CSPI are not the first to object to Happy Meal toys — in early November, San Francisco’s city council agreed to ban toys from the packaged meals unless they met nutritional criteria for salt, sugar, fat and calories, as well as a fruit or vegetable component. (More on Time.com:Judge to McDonald’s: Pay $17,500 For Making Your Employee Fat)

Previously, CSPI has sued Kellogg’s for advertising unhealthy cereals to young children and KFC for its use of partially-hydrogenated oil, which made the fried items on its menu high in trans fats. Both suits were settled when Kellogg’s and KFC implemented internal reforms.